Documentation needed? - `module_true` interferes with require return value

[wesQ3]

Description Using feature module_true changes the return value of a required file but this is not shown in the require documentation. I expect that behavior if the required file isn't already returning a true value, but I did not expect it to alter what was already a true return value.

This is simple to work around with a no feature 'module_true' but I first had to realize that it was part of the 5.40 feature bundle. My project recently updated to 5.40 so this was the first migration I have written with the new feature bundle.

Steps to Reproduce This demo shows the behavior I saw using DBIx::Class::DeploymentHandler. DeploymentHandler runs Perl migration scripts contained in a directory by wrapping each in a package and requireing it. The loaded migration script is expected to return a subref to be run by the DH DeployMethod. I was unable to return the subref until I disabled the module_true feature.

demo.pl

#! /usr/bin/env perl

use strict; use warnings;
use feature 'say';
use lib '.';
use Carp 'croak';
use Digest::MD5 'md5_hex';
use Try::Tiny;

# Adapted from lib/DBIx/Class/DeploymentHandler/DeployMethod/SQL/Translator.pm
sub _load_sandbox {
  my $_file = shift;
  $_file = "$_file";
  # my $_package = _generate_script_package_name($_file);
  my $_package = 'A::Package::'.md5_hex("$_file");
  my $fn = eval sprintf <<'END_EVAL', $_package;
package %s;
{
  our $app;
  $app ||= require $_file;
  if ( !$app && ( my $error = $@ || $! )) { die $error; }
  $app;
}
END_EVAL
  croak $@ if $@;
  croak "$_file should define an anonymous sub that takes a schema but it didn't!"
     unless ref $fn && ref $fn eq 'CODE';
  return $fn;
}
sub _run_perl {
  my ($filename, $versions) = @_;
  say "Running Perl from $filename";
  my $fn = _load_sandbox($filename);
  try {
     # $fn->($self->schema, $versions)
     $fn->()
  } catch {
     die "failed to run Perl in $filename: $_"
  };
  say "\n";
}

_run_perl('no_module_true.pl');
_run_perl('use_module_true.pl');

no_module_true.pl

#!/usr/bin/env perl

use v5.40; use warnings;
no feature 'module_true';

sub {
   say 'module_true disabled';
};

use_module_true.pl

#!/usr/bin/env perl

use v5.40; use warnings;

sub {
   say 'using module_true';
};

Expected behavior

According to the require doc the module_true feature simply allows you to "avoid the requirement" of returning a true value. I was already returning a truthy value so I was surprised that the feature clobbered my returned subref.

Perl configuration

This is perl 5, version 40, subversion 2 (v5.40.2) built for x86_64-linux

``` Summary of my perl5 (revision 5 version 40 subversion 2) configuration:

Platform: osname=linux osvers=6.8.0-51-generic archname=x86_64-linux uname='linux bigboss 6.8.0-51-generic #52-ubuntu smp preempt_dynamic thu dec 5 13:09:44 utc 2024 x86_64 x86_64 x86_64 gnulinux ' config_args='-Dprefix=/home/wes/.plenv/versions/5.40.2 -de -Dversiononly -A'eval:scriptdir=/home/wes/.plenv/versions/5.40.2/bin'' hint=recommended useposix=true d_sigaction=define useithreads=undef usemultiplicity=undef use64bitint=define use64bitall=define uselongdouble=undef usemymalloc=n default_inc_excludes_dot=define Compiler: cc='cc' ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64' optimize='-O2' cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include' ccversion='' gccversion='13.3.0' gccosandvers='' intsize=4 longsize=8 ptrsize=8 doublesize=8 byteorder=12345678 doublekind=3 d_longlong=define longlongsize=8 d_longdbl=define longdblsize=16 longdblkind=3 ivtype='long' ivsize=8 nvtype='double' nvsize=8 Off_t='off_t' lseeksize=8 alignbytes=8 prototype=define Linker and Libraries: ld='cc' ldflags =' -fstack-protector-strong -L/usr/local/lib' libpth=/usr/local/lib /usr/lib/x86_64-linux-gnu /usr/lib /usr/lib64 libs=-lpthread -ldl -lm -lcrypt -lutil -lc perllibs=-lpthread -ldl -lm -lcrypt -lutil -lc libc=/lib/x86_64-linux-gnu/libc.so.6 so=so useshrplib=false libperl=libperl.a gnulibc_version='2.39' Dynamic Linking: dlsrc=dl_dlopen.xs dlext=so d_dlsymun=undef ccdlflags='-Wl,-E' cccdlflags='-fPIC' lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'

Characteristics of this binary (from libperl): Compile-time options: HAS_LONG_DOUBLE HAS_STRTOLD HAS_TIMES PERLIO_LAYERS PERL_COPY_ON_WRITE PERL_DONT_CREATE_GVSV PERL_HASH_FUNC_SIPHASH13 PERL_HASH_USE_SBOX32 PERL_MALLOC_WRAP PERL_OP_PARENT PERL_PRESERVE_IVUV PERL_USE_SAFE_PUTENV USE_64_BIT_ALL USE_64_BIT_INT USE_LARGE_FILES USE_LOCALE USE_LOCALE_COLLATE USE_LOCALE_CTYPE USE_LOCALE_NUMERIC USE_LOCALE_TIME USE_PERLIO USE_PERL_ATOF Built under linux Compiled at Apr 30 2025 13:58:29 @INC: /home/wes/.plenv/versions/5.40.2/lib/perl5/site_perl/5.40.2/x86_64-linux /home/wes/.plenv/versions/5.40.2/lib/perl5/site_perl/5.40.2 /home/wes/.plenv/versions/5.40.2/lib/perl5/5.40.2/x86_64-linux /home/wes/.plenv/versions/5.40.2/lib/perl5/5.40.2

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